[PATCH v5 11/18] reftable/system: introduce `reftable_rand()`

[Patrick Steinhardt <ps@pks.im>]

Introduce a new system-level `reftable_rand()` function that generates a
single unsigned integer for us. The implementation of this function is
to be provided by the calling codebase, which allows us to more easily
hook into pre-seeded random number generators.

Adapt the two callsites where we generated random data.

Signed-off-by: Patrick Steinhardt <ps@pks.im>
---
 reftable/stack.c  | 4 ++--
 reftable/system.c | 5 +++++
 reftable/system.h | 6 ++++++
 3 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/reftable/stack.c b/reftable/stack.c
index 46abf51ec5..e22577ec77 100644
--- a/reftable/stack.c
+++ b/reftable/stack.c
@@ -523,7 +523,7 @@ static int reftable_stack_reload_maybe_reuse(struct reftable_stack *st,
 		close(fd);
 		fd = -1;
 
-		delay = delay + (delay * git_rand(CSPRNG_BYTES_INSECURE)) / UINT32_MAX + 1;
+		delay = delay + (delay * reftable_rand()) / UINT32_MAX + 1;
 		sleep_millisec(delay);
 	}
 
@@ -688,7 +688,7 @@ int reftable_stack_add(struct reftable_stack *st,
 static int format_name(struct reftable_buf *dest, uint64_t min, uint64_t max)
 {
 	char buf[100];
-	uint32_t rnd = git_rand(CSPRNG_BYTES_INSECURE);
+	uint32_t rnd = reftable_rand();
 	snprintf(buf, sizeof(buf), "0x%012" PRIx64 "-0x%012" PRIx64 "-%08x",
 		 min, max, rnd);
 	reftable_buf_reset(dest);
diff --git a/reftable/system.c b/reftable/system.c
index adf8e4d30b..e25ccc0da3 100644
--- a/reftable/system.c
+++ b/reftable/system.c
@@ -4,6 +4,11 @@
 #include "../lockfile.h"
 #include "../tempfile.h"
 
+uint32_t reftable_rand(void)
+{
+	return git_rand(CSPRNG_BYTES_INSECURE);
+}
+
 int tmpfile_from_pattern(struct reftable_tmpfile *out, const char *pattern)
 {
 	struct tempfile *tempfile;
diff --git a/reftable/system.h b/reftable/system.h
index 7d5f803eeb..3bd4a4e322 100644
--- a/reftable/system.h
+++ b/reftable/system.h
@@ -13,6 +13,12 @@ license that can be found in the LICENSE file or at
 
 #include "git-compat-util.h"
 
+/*
+ * Return a random 32 bit integer. This function is expected to return
+ * pre-seeded data.
+ */
+uint32_t reftable_rand(void);
+
 /*
  * An implementation-specific temporary file. By making this specific to the
  * implementation it becomes possible to tie temporary files into any kind of

-- 
2.48.1.538.gc4cfc42d60.dirty